General Turbo question

[Ss82]

See alot cars had td03 td04 blah blah blah

Take it there not the exact same turbo since all the cars are completely different power wise....why are they called the same? Is the internals all the same but size of outside casing smaller?

[Ss82]

Sorry I shouldv worded it better lol say a scoob has a td04 n a audi has a td04 surely there not the same unit?

Thanks for the answer tho :)